Cheney Exit, Rice Entry Could Alter 2008 Race
Although only 66, Cheney has suffered four heart attacks in the past and has undergone angioplasty and bypass surgery. This week, he was diagnosed with a blood clot in his leg. Blood clots can travel to the lungs and result in a pulmonary embolism - a sudden blockage of blood flow in an artery in the lung - one of the leading causes of death in the U.S.
In the event of the vice presidency becoming vacant through resignation or death, the Constitution requires the president to nominate a vice president who must be confirmed by majority vote of both houses of Congress.
Bush would find it difficult to get a Democratic-controlled Congress to approve a conservative nominee, analysts say. At the same time, neither of the leading GOP 2008 presidential aspirants - former New York City Mayor Rudy Giuliani or Sen. John McCain of Arizona - would be eager to be seen as President Bush's heir apparent, should he tap either of them for the job.